partial bitcoin#18587: Avoid wallet tryGetBalances calls in WalletModel::pollBalanceChanged

contains:
- 2bc9b92ed8b7736ad67876398a0bb8287f57e9b3
- bf0a510981ddc28c754881ca21c50ab18e5f2b59

src/qt/walletmodel.cpp

@@ -39,7 +39,7 @@
 WalletModel::WalletModel(std::unique_ptr<interfaces::Wallet> wallet, ClientModel& client_model, QObject *parent) :
     QObject(parent),
     m_wallet(std::move(wallet)),
-    m_client_model(client_model),
+    m_client_model(&client_model),
     m_node(client_model.node()),
     optionsModel(client_model.getOptionsModel()),
     addressTableModel(nullptr),
@@ -47,7 +47,8 @@ WalletModel::WalletModel(std::unique_ptr<interfaces::Wallet> wallet, ClientModel
     recentRequestsTableModel(nullptr),
     cachedEncryptionStatus(Unencrypted),
     cachedNumISLocks(0),
-    cachedCoinJoinRounds(0)
+    cachedCoinJoinRounds(0),
+    timer(new QTimer(this))
 {
     fHaveWatchOnly = m_wallet->haveWatchOnly();
     addressTableModel = new AddressTableModel(this);
@@ -65,11 +66,16 @@ WalletModel::~WalletModel()
 void WalletModel::startPollBalance()
 {
     // This timer will be fired repeatedly to update the balance
-    QTimer* timer = new QTimer(this);
     connect(timer, &QTimer::timeout, this, &WalletModel::pollBalanceChanged);
     timer->start(MODEL_UPDATE_DELAY);
 }
 
+void WalletModel::setClientModel(ClientModel* client_model)
+{
+    m_client_model = client_model;
+    if (!m_client_model) timer->stop();
+}
+
 void WalletModel::updateStatus()
 {
     EncryptionStatus newEncryptionStatus = getEncryptionStatus();
@@ -85,6 +91,10 @@ void WalletModel::pollBalanceChanged()
         return;
     }
 
+    // Avoid recomputing wallet balances unless a TransactionChanged or
+    // BlockTip notification was received.
+    if (!fForceCheckBalanceChanged && m_cached_last_update_tip == m_client_model->getBestBlockHash()) return;
+
     // Try to get balances and return early if locks can't be acquired. This
     // avoids the GUI from getting stuck on periodical polls if the core is
     // holding the locks for a longer time - for example, during a wallet

src/qt/walletmodel.h

@@ -198,7 +198,8 @@ public:
 
     interfaces::Node& node() const { return m_node; }
     interfaces::Wallet& wallet() const { return *m_wallet; }
-    ClientModel& clientModel() const { return m_client_model; }
+    void setClientModel(ClientModel* client_model);
+    ClientModel& clientModel() const { return *m_client_model; }
     interfaces::CoinJoin::Client& coinJoin() const { return m_wallet->coinJoin(); }
 
     QString getWalletName() const;
@@ -218,7 +219,7 @@ private:
     std::unique_ptr<interfaces::Handler> m_handler_show_progress;
     std::unique_ptr<interfaces::Handler> m_handler_watch_only_changed;
     std::unique_ptr<interfaces::Handler> m_handler_can_get_addrs_changed;
-    ClientModel& m_client_model;
+    ClientModel* m_client_model;
     interfaces::Node& m_node;
 
     bool fHaveWatchOnly;
@@ -235,6 +236,7 @@ private:
     // Cache some values to be able to detect changes
     interfaces::WalletBalances m_cached_balances;
     EncryptionStatus cachedEncryptionStatus;
+    QTimer* timer;
     int cachedNumISLocks;
     int cachedCoinJoinRounds;
 

src/qt/walletview.cpp

@@ -145,6 +145,7 @@ void WalletView::setClientModel(ClientModel *_clientModel)
     if (settings.value("fShowGovernanceTab").toBool() && governanceListPage != nullptr) {
         governanceListPage->setClientModel(_clientModel);
     }
+    if (walletModel) walletModel->setClientModel(_clientModel);
 }
 
 void WalletView::setWalletModel(WalletModel *_walletModel)